As the newest input devices, touch screens are the easiest, the most convenient and the most natural means for human-machine interaction, and have enormous development potential. A touch screen typically comprises: a touch element for implementing the touch function, a liquid crystal device (LCD) panel for implementing the display function, and a protective cover glass. The touch element may be fabricated on the base substrate to form a separate touch screen, and then the touch screen is bonded to the LCD panel and the cover glass. Alternatively, the touch element may be fabricated on the cover glass directly, and then the cover glass is bonded to the LCD panel. As another alternative, the touch element may be disposed in the LCD panel, and then the cover glass is bonded to the LCD panel. Any of the above structures need to bond the cover glass to parts such as LCD panels in the end, and such a step is referred to as the bonding process. If optic clear resin (OCR) adhesives are employed in the bonding process, the adhesives are generally coated by way of slit coating. As illustrated in FIG. 1, a slit nozzle 12 sprays the OCR while moves from left to right relative to a cover glass 10, thus forming an OCR coating 11 with good flatness on a bonding surface of the cover glass 10. However, comparing with the middle stage of the coating process, the coating speed at the starting and ending stages of the coating process are relatively slow. Due to the residence of liquid, the thicknesses of the starting and the ending parts of the OCR coating are much larger than that the middle part, easily causing air bubbles to be generated and difficulties in controlling the adhesive overflow, thereby decreasing the free-defect ratio of bonding.